Uterine fibroids, according to the Mayo Clinic, are “noncancerous growths of the uterus that often appear during childbearing years.” They can range in size from tiny seedlings to bulky masses.

According to John Hopkins Medicine, uterine fibroids occur in about 77% of women at some point during their reproductive age, and at any any given time, 20-50% of women of reproductive age are experiencing fibroids.

“Uterine fibroids, also caused by leiomyomas, are benign (noncancerous) growths of the uterus, mainly the uterine muscle,” explained Karyn S. Eilber, M.D., a board-certified female pelvic medicine and reconstructive surgery specialist at Cedars-Sinai Hospital in California, to Glamour.

Here are five things you should know about fibroids:

What are the symptoms?

While fibroids themselves don’t cause any specific symptoms — many women aren’t even aware they have them — larger growths may put pressure on organs or otherwise impact normal body functions. If you’ve experienced any of these symptoms, you might want to consult with your doctor about the possibility of having developed uterine fibroids.

  • Heavy bleeding (which can sometimes cause anemia) or painful periods
  • A feeling of fullness in the pelvic area
  • Enlargement of the lower abdomen
  • Frequent urination
  • Pain during sex
  • Lower back pain

Reproductive problems, including infertility, have been reported due to uterine fibroids, but this seems to be very rare.

They can be painful

The pain caused by larger fibroids can be severe. It can leave sufferers feeling swollen and cause discomfort when lying down, bending over and walking.

In some cases, fibroids can cause pelvic pain, lower back pain and even pain during sex.

“Pain caused by fibroids can significantly affect a person’s quality of life,” said Verywell Health.

Can fibroids be prevented?

There are multiple reasons why fibroids develop; and while scientists definitely believe there’s a genetic component, a condition that affects so many women will inevitably have multiple risk factors.

“If someone could figure out what causes fibroids and how to prevent them, they would probably win a Nobel prize,” Dr. Eilber added.

In short, there’s nothing any individual can do to prevent developing uterine fibroids entirely. That said, some factors which increase the likelihood of developing them include:

  • Obesity
  • High blood pressure
  • Vitamin D deficiency
  • Never having been pregnant

Fibroids are more common in Black women

Black women are three times more likely to be diagnosed with fibroids than women of other races. And they’re more likely to experience them earlier in life, which often leads to surgical intervention.

Environmental and health disparities — like vitamin D deficiency — may explain some of the additional risk, according to McLeod Health, but there may also be genetic factors at play, as evidenced by the fact that Black women with roots in certain regions experience higher frequency of fibroids, even if they don’t live in that region.

“We know that ethnicities such as Nigerian, Ethiopian, and Ghanaian have higher rates of fibroids than other ethnicities, even in the African American and African communities,” Dr. Ruth Arumala, D.O., an OB-GYN and fibroid specialist in Texas, told Glamour.

How do fibroids impact pregnancy and fertility?

Most women with uterine fibroids have perfectly ordinary pregnancies, followed by natural deliveries. However, fibroids can be a risk factor for requiring a delivery by C-section. In rare cases, patients experience pre-term labor and other complications. Those at most risk are women with multiple fibroid growths or very large fibroids (larger than 5 cm).

As for getting pregnant, fibroids have no inherent impact on fertility, but the growth of fibroids in certain key locations could make getting pregnant more difficult or even impossible.

“In the endometrial cavity, a fibroid can impact the implantation of the fertilized egg, or if the fibroid is situated where it’s blocking the fallopian tube, the egg can’t get to the sperm,” explained Jessica Shepherd, M.D., chief medical officer at Verywell Health and a board-certified OB-GYN and fibroid expert.